Molecular Aspects of B-Glucan Biosynthesis in Higher Plants

高等植物中β-(1，3)连接的葡聚糖和可能的纤维素的生物合成是由质膜酶葡聚糖合成酶(UDP-葡萄糖：(1，3)-β-葡聚糖合成酶)催化的。为了了解细胞壁多糖生物合成和伤口愈合的调控的生化基础，有必要对多糖合酶进行鉴定和鉴定。葡聚糖合成酶在植物组织中普遍存在，但已被证明是一种顽固的酶，通过标准的蛋白质分级技术纯化到均一。现在，使用洗涤剂CHAPS的差异性增溶、凝胶过滤层析和产品包埋，可以从一系列植物来源获得稳定和高度浓缩的酶制剂。这项研究将解决长期存在的问题，即β-(1，3)和β-(1，4)连接的葡聚糖是由一种酶还是由几种酶生物合成的，其中每种酶对形成一种连接类型都是不同的。此外，明确识别组成葡聚糖合成酶复合体的多肽将有助于鉴定和克隆编码植物细胞壁生物发生中重要酶的一个或多个基因。纤维素是一种极其丰富的生物聚合物，在植物细胞中起着结构性的作用。由于从细胞壁中分离所涉及的酶很困难，人们对其生物合成的了解还不完全。这个项目的重点是主要受调控的酶，并将提供有关细胞壁是如何形成和保持完好无损的重要信息。

The biosynthesis of beta-(1,3) linked glucans and possibly cellulose in higher plants is catalyzed by the plasma membrane enzyme glucan synthase (UDP-glucose:(1,3)-beta-glucan synthase). To understand the biochemical basis for the regulation of cell wall polysaccharide biogenesis and wound healing, it is necessary to identify and characterize the polysaccharide synthases. Glucan synthase is ubiquitous in plant tissue but has proven to be a stubborn enzyme to purify to homogeneity by standard protein fractionation techniques. It is now possible to obtain stabilized and highly-enriched enzyme preparations from a range of plant sources using differential solubilization with the detergent CHAPS, gel filtration chromatography and product entrapment. This research will resolve the longstanding question of whether beta-(1,3) and beta-(1,4) linked glucans are biosynthesized by one enzyme or by several where each is distinct for the formation of one linkage type. Furthermore, unambiguous identification of the polypeptides which comprise the glucan synthase complex will facilitate identification and cloning of the gene or genes which code for important enzymes in plant cell wall biogenesis. Cellulose, an immensely abundant biopolymer, serves a structural role in plant cells. Its biosynthesis is only incompletely understood because of the difficulties in isolating the enzymes involved from cell walls. This project focuses on the major regulated enzyme and will provide important information on how cell walls are made and kept intact.